Low Intermediate Frequency (LIF) receivers have been proposed for use in wireless networks to provide improved sensitivity and noise characteristics. Generally, communication signals are transmitted at a desired frequency, fo, obtained by multiplying the original base band signal by a carrier frequency. In a Low-IF receiver, the desired frequency, RF, is first down-converted to an intermediate frequency, IF, so that the unwanted DC content can be filtered out, before further down conversion is performed to the information carrying base band signal, in a known manner. The down-conversion process at the receiver causes adjacent channel interference (ACI) at a frequency of LO−IF, as shown in FIG. 1.
These partial images of the desired frequency signal on each side of the desired frequency cannot be filtered out. Thus, following the down conversion process, the adjacent channel interference will cause distortion in adjacent channels (i.e., increased out-of-channel energy). Thus, Low-IF receivers are said to exhibit poor performance for handling adjacent signals. Nonetheless, Low-IF receivers demonstrate superior sensitivity since they do not suffer from in-channel distortion, such as DC offset and IQ imbalance distortion. A need therefore exists for a low IF receiver that exhibits improved adjacent channel rejection.